Rock drill



April 28, 1964 R. w. BEAUMONT ROCK DRILL lf'iled Oct. 5, 1960 INVENTOR RICHARD (BEAUMONT H. km

United States Patent New Jersey Filed Oct. 5, 1960, Ser. No. 60,698 2 Claims. ((11. 175-293) This invention relates to rock drills, and more particularly to the down hole rotary percussion type of rock drills.

In many instances the type of drill above referred to is provided with a rotating mechanism which turns the rock drill and the percussive drill bit connected thereto at a substantially constant speed for the purpose of presenting a new rock surface to the drill bit cutting edges. There are some instances in which this rotation is not without disadvantages, among these are cases where the rock drill is being urged forwardly with a very considerable thrust producing a grinding of the cutting edges against the bottom of the hole being drilled which greatly shortens their useful life. Apparatuses for counter-balancing the weight of the drill to reduce such grinding effect have not been very satisfactory because the lifting effort required to relieve the pressure on the drill bit varies and so the effect is uncertain.

The provision of rollers or roller cutters attached to the drill casing and extending forwardly therefrom to support the weight of the drill in addition to chipping the rock formation, while a percussive drill bit struck by the reciprocating piston within the drill casing fractures the rock is not very satisfactory and reliable either. The bearings supporting the rollers, being of necessity small, usually fail after a short period of time because of the extensive weight of the drill. In addition thereto, impurities penetrating the bearings, considerably shorten the operational life of the bearings.

It is then an object of this invention to reduce the thust of such drills upon the drill bit and to reduce the wear on the cutting edges of the drill bit.

Other objects and advantages of the invention will be in part obvious and in part pointed out hereinafter.

The drawing illustrates an improved and preferred embodiment of the invention and includes FIGURE 1, showing the fore part of the improved rock drill in longitudinal section,

FIG. 2 is an end view of the face of the drill bit,

FIG. 3 is a section taken along the line 33 of FIG. 1 and looking in the direction of the arrows, and

FIG. 4 is a section taken along the line 4-4 of FIG. 1 and looking in the direction of the arrows.

Referring to the drawing the rock drill of which the important parts are shown is of the type which is adapted to follow the bit down the hole being drilled and may in its motive mechanism be of any well known construction of that type and includes a casing somewhat smaller in diameter than the drill bit 12 so that it may follow that bit into a hole in a rock formation indicated at 14. Within casing 10 is provided a reciprocatory hammer element 16 of which the nose portion only is shown and which is guided in an element 18 generally called a front cylinder washer. Casing 10 is preferably cylindrical and hollow and is adapted to receive the rearward portion or shank 20 of bit 12 which being in the path of hammer 16 is adapted to be struck for transmitting blows to suitable cutting edges 22 provided on the forward portion 24 of the drill bit protruding from casing 10.

Drill bit 12 is adapted to slide with a limited amount of longitudinal movement within the front end portion of casing 10. It is provided with a shoulder or head 21 and a reduced portion 32. A retaining ring 30 held in ice position within casing 10 between sleeve 26 and retainer nut 28 cooperates with reduced portion 32 and head 21 to prevent the drill bit from being unintentionally withdrawn from the casing.

The front end of bit 24 is provided with wings 34 as is usual with rock drill bits, the space between the wings being adapted to allow the cuttings to pass out of the hole by washing with water, air under pressure or any suitable cleansing fluid. In this instance the bit is of cross variety although the wings are not entirely perpendicular to each other as is often the case.

It is to be understood that the weight of the apparatus which includes the weight of the casing itself and whatever may be superposed upon it, constitutes mostly a considerable thrust which is received by the casing 10. This considerable thrust is transmitted to bit 12 and more in particular to the cutting edges thereof causing the cutting edges of the bit, as the drill rotates, to be ground off in short order.

This invention provides means for preventing the thrust upon casing 10 from being transmitted to the cutting edges 22, and to this end is provided a member 36 to which the casing thrust is transmitted. Preferably member 36 is of some hard material such as metal and in this instance is in the form of a pin carried by a heavy plate 38 movably mounted in an aperture in the form of a slot 40 in the face of bit 12 and somewhat deeper than plate 38. As shown in FIG. 2 slot 40 extends lengthwise of one pair of wings 34 so as to provide substantial strength to support plate 38. To transmit the thrust from casing 10 to plate 38 there are provided a pair of rods 42 longitudinally slidable within the outer periphery of the drill bit and extending upwardly into casing 10 and bearing against front cylinder washer 18 at their innermost ends. At the forward ends they are adapted to engage plate 38 being slotted as at 44 to receive the reduced ends 46 of plate 38. The shank 20 is grooved as at 48 to receive and guide rods 42. The protruding portion 24 of bit 12 is provided with bores 50 in alignment with grooves 48 to slidably accommodate the forward end portions of rods 42.

It will thus be seen that the weight and whatever thrust there may be on casing 10 will be transmitted through rods 42 to the plate 38 and pin 36 directly to the face of the rock formation 14 while bit 12 will dance more or less freely on the rock face as a result of being struck by the hammer 16. In any case while the entire assembly is rotated, the weight on the cutting edges 22 will be relatively slight and abrision will be thus quite minimized.

Hammer 16 is shown with a central bore 52 which registers with a corresponding bore 54 in drill bit 12, both bores constituting a conduit for the accommodation of cleansing air passing from the drill to the face of the rock 14 being cut. Additional cleansing air is introduced by Way of flutes 56 extending longitudinally of hammer 16. Air thus introduced passes into bore 54 when hammer 16 is withdrawn from the end of the shank 20.

Thus, are accomplished, among others, the objects hereinbefore referred to.

I claim:

1. A rock drill comprising a thrust receiving casing, a hammer reciprocable within the casing, a reciprocatory drill bit having a portion slidably positioned in said casing to be struck by said hammer and a portion protruding from said casing provided with rock cutting edges, and an aperture in said drill bit positioned transversely relative to the longitudinal axis of said drill bit, a member in said aperture longitudinally movable therein relative to said drill bit and extending substantially to said cutting edges, and elongated rods slidably extending through said drill bit and positioned longitudinally of and radially displaced from the longitudinal axis of said drill bit and having one of their ends in engagement with said casing and the other ends in engagement with said member to transmit thrust from said casing to said movable member and to the bottom of the hole being drilled, the length of said rods and said member being such to cause constant engagement of said drill bit with the bottom of the hole being drilled when said casing is supported by said rods and said member on the bottom of the hole being drilled.

2. A rock drill comprising a thrust receiving casing, a hammer reciprocable within the casing, a reciproeatory drill bit having a portion slidably positioned in said casing to be struck by said hammer and a portion protruding from said casing provided with rock cutting edges, and an aperture positioned transversely relative to the longitudinal axis of said drill bit and centrally in the forward end portion of said drill bit, a member in said aperture longitudinally movable therein relative to said drill bit and having a central portion extending substantially to said cutting edges, and elongated rods slidably extending through said drill bit and positioned longitudinally of and radially evenly displaced from the longitudinal axis of said drill bit and abuttingly positioned between said casing and said member to transmit thrust from said casing to said movable member and to the bottom of the hole being drilled, the distance between the rearward ends of said rods and the forward end of said member being such to cause constant engagement of said drill bit with the bottom of the hole being drilled when said casing is supported by said rods and said member on the bottom of the hole being drilled.

References Cited in the file of this patent UNITED STATES PATENTS 1,372,257 Swisher Mar. 22, 1921 2,345,024 Bannister Mar. 28, 1944 2,873,093 Hildebrandt et a1 Feb. 10, 1959 

1. A ROCK DRILL COMPRISING A THRUST RECEIVING CASING, A HAMMER RECIPROCABLE WITHIN THE CASING, A RECIPROCATORY DRILL BIT HAVING A PORTION SLIDABLY POSITIONED IN SAID CASING TO BE STRUCK BY SAID HAMMER AND A PORTION PROTRUDING FROM SAID CASING PROVIDED WITH ROCK CUTTING EDGES, AND AN APERTURE IN SAID DRILL BIT POSITIONED TRANSVERSELY RELATIVE TO THE LONGITUDINAL AXIS OF SAID DRILL BIT, A MEMBER IN SAID APERTURE LONGITUDINALLY MOVABLE THEREIN RELATIVE TO SAID DRILL BIT AND EXTENDING SUBSTANTIALLY TO SAID CUTTING EDGES, AND ELONGATED RODS SLIDABLY EXTENDING THROUGH SAID DRILL BIT AND POSITIONED LONGITUDINALLY OF AND RADIALLY DISPLACED FROM THE LONGITUDINAL AXIS OF SAID DRILL BIT AND HAVING ONE OF THEIR ENDS IN ENGAGEMENT WITH SAID CASING AND THE OTHER ENDS IN ENGAGEMENT WITH SAID MEMBER TO TRANSMIT THRUST FROM SAID CASING TO SAID MOVABLE MEMBER AND TO THE BOTTOM OF THE HOLE BEING DRILLED, THE LENGTH OF SAID RODS AND SAID MEMBER BEING SUCH TO CAUSE CONSTANT ENGAGEMENT OF SAID DRILL BIT WITH THE BOTTOM OF THE HOLE BEING DRILLED WHEN SAID CASING IS SUPPORTED BY SAID RODS AND SAID MEMBER ON THE BOTTOM OF THE HOLE BEING DRILLED. 